The present invention relates to systems for transporting material and people up and down ramps, and more particularly to systems for transporting material and people up and down a variably-inclinable ramp in a carriage configured to maintain a generally horizontal orientation.
Ramps are used to transport material between two sites having different elevations. It is well known, for example, to use a ramp to move heavy articles from the ground into a truck.
It is also well known to move people up and down ramps. In particular, ramps are often employed to move people in wheelchairs and other similar devices between two sites having different elevations. Such xe2x80x9cwheelchair rampsxe2x80x9d are ubiquitous in our society nowadays, and such ramps are indeed often mandated by modern building codes to ease the mobility of those in wheelchairs and generally to assist in the transportation of people using such devices.
Despite the fact that wheelchair ramps and other ramps are now commonplace, however, those in wheelchairs still face difficulties traversing some of these ramps. In some instances, a ramp might be too steep to allow the wheelchair-bound person to push the wheelchair up the ramp alone without assistance. Such assistance might be provided by another person, but it is also common to provide such assistance by means of some motorized system. In many such motorized systems, a carriage is provided which can accept the wheelchair, and which can then be moved from the lower end of the ramp to the upper end (and, of course, vice versa). It is not uncommon for such motorized systems to be constructed to allow a person to remain in their wheelchair, but if this is the case, it is much preferred that the wheelchair maintain a typical, generally horizontal orientation.
While it is relatively straightforward to provide an effective motorized ramp system to transport a wheelchair in a generally horizontal orientation where the degree of incline between a lower site and an upper site is invariable, it is much more difficult to provide a system which will maintain this generally horizontal orientation in a situation where the incline can vary. One very common such situation is that which will be familiar to those who live in marine environments. It is very common to have variably-inclinable ramps extending between the shore (or a fixed dock extending out from the shore) and a floating dock situated upon the surface of the water.
It should be readily understood that the angle of incline of such a ramp, if the ramp is of a fixed length, varies according to the relative elevations between the upper, fixed dock, and the lower, floating dock. The difference in relative elevations, in turn, varies depending upon the water level. In many marine environments (for example, on the ocean), where the action of tides can cause a significant variation in water levels, the degree of inclination of such ramps can pass through a wide range. At low tide, the ramp will be steep, and accordingly difficult for a person in a wheelchair to traverse.
Further, it might be dangerous for the wheelchair-bound person to attempt to traverse a ramp in a marine environment when surrounding environmental conditions are poor. A carriage for securing the wheelchair is therefore desirable.
Attempts have been made to construct systems which can maintain some object in a generally horizontal, or upright, orientation when the object is moved up a variable incline. Indeed, an attempt has been made to describe such a system which might have application in a marine environment. U.S. Pat. No. 6,105,726 discloses a variable-incline ramp system for maintaining a vehicle in a horizontal orientation, and that patent states therein that the system might be employed in a marine environment. This system uses a set of four rails along which are able to move four wheels attached to a platform. It is unlikely that this system would be realistically employed in a marine environment, however. First, it could not be easily retrofitted onto an existing dock. Second, the platform of the system does not permit a wheelchair to be safely contained within a carriage to prevent the wheelchair from slipping off the ramp. Structural limitations of this system also prevent regular, non-wheelchair bound persons from using the ramp in a typical fashion.
What remains necessary, accordingly, is a ramp system for allowing the movement of people and materials through an incline while maintaining them in their generally horizontal or upright orientation, notwithstanding the variable degree of incline. The present invention is directed to such a system.
The present invention provides a ramp system for transporting material between a first site and a second site, the first site having a lower elevation than the second site, the system comprising first and second rails extending between the first and second sites, the first and second rails pivotally attached at one end to the second site at first and second lower attachment points respectively, each rail bearing an upwardly extending support member near its opposite end. A carriage is provided for carrying the material, the carriage having a frame comprising a front portion, a lower rear portion and an upper rear portion. A plurality of wheels are attached to the lower rear portion of the carriage for engaging the rails. A first upper pulley is attached to the upper rear portion of the frame on one side thereof, and a second upper pulley is attached to the upper rear portion of the frame on the opposite side thereof. A first lower pulley is attached to the lower rear portion of the frame on one side thereof, and a second lower pulley is attached to the lower rear portion of the frame on the opposite side thereof.
A first cable is attached at one end to a first upper attachment point on the second site, the first upper attachment point located at a higher elevation than the first lower attachment point, and the first cable is attached at an opposite end to the bottom portion of the support member on the first rail. The first cable extends from the first upper attachment point over the first upper pulley and under the first lower pulley. A second cable is attached to a second upper attachment point on the second site, the second upper attachment point located at a higher elevation than the second lower attachment point. The second cable is attached at an opposite end to the bottom portion of the support member on the second rail. The second cable extends from the second upper attachment point over the second upper pulley and under the second lower pulley. Also provided are means for providing motive force to the carriage to move it up and down the rails between the said first and second sites.